Chrome Version: 51.0.2704.0
Chrome OS Version: 8172.1.0
Chrome OS Platform: All
Network info: WiFi

Please specify Cr-* of the system to which this bug/feature applies (add
the label below).

Steps To Reproduce:
(1) From the bug comment https://bugs.chromium.org/p/chromium/issues/detail?id=585723#c9

(2)Download video file locally
(3) Check type of file
(4) Play file in internal player
(5) Observe it plays on audio player
(6) Play file in HTML5 player by playing file in browser
(7) Observe file play as a video file

Expected Result:
Expecting it behaves same on both the players

Actual Result:
In internal player it detects as a audio player, but in HTML5 player it detects as a video player

How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)
Always
What is the impact to the user, and is there a workaround? If so, what is
it?

Please provide any additional information below. Attach a screen shot or
log if possible.